Engine oil temperature for optimal lubrication - 5cylinderdiesel

Hi

Does anybody have any knowledge of what the optimal engine oil temperature is for optimal engine wear protection and also how long does one need to drive (moderate speed) to get the oil to that temperature? And is there anyone with any technical knowledge on the wear patterns in an engine from start up and over the first 10 - 20 minutes of driving?

Thanks

Engine oil temperature for optimal lubrication - bathtub tom

Start it, drive it. Don't sit there and let it 'warm up'.

Let the thermostat do the rest.

Tell us the full story?

Engine oil temperature for optimal lubrication - unthrottled

Generally speaking, optimum sump temperature is 80-100C. Sump temperatures up to ~120C are ok, albeit with increased oil oxidation.

Oil warm up is slow-much slower than coolant. 15-20 minutes from cold start would be a ball park figure. Oil temperature sensors located in the oil return line give a false perception since the important figure during warm-up is the temperature of the oil entering the system.

The optimum sump oil temperature is dependant on how heavily the engine is loaded (optimum temperature inversely proportional to load).

Optimum oil temperature also depends on engine speed (optimum temperature increases with RPM)

There's not a great deal you can do to tightly control the temperatures but if you go easy for the first 10-15 minutes, you'll minimise wear.

Oil temperature has a strong dependancy on RPM, so you can use engine braking to help warm up the oil if you're concerned.

Bathtub Tom isn't wrong; most engines survive a complete disregard for oil temps :)

Engine oil temperature for optimal lubrication - Armitage Shanks {p}

On the basis of what you say, UT, which sounds 100% correct and sensible, I can't imagine how I was conned into buying and fitting an oil cooler for my bog standard MG-B! It did have a thermostat and I can't imagine that any oil ever went through it, we way I drove!

I did have an oil temp gauge in a Mk 1 Golf GTi and always kept an eye on that. It came in useful on a continental touring holiday when the oil pressure warning light failed so I had a crude indication of the state of affairs via the temp gauge

Engine oil temperature for optimal lubrication - RT

Some cars do get a fluid-to-fluid cooler/heater for the engine oil - both my Subaru Outback and Hyundai Santa Fe had/have them - I only discovered when removing undershields to do oil changes and discovered an unexpected device next to the oil filter with pipes which lead back to the cabin heater circuit.

As the engine coolant is running at 85-90 degrees C, consistently in all normal conditions this provides a very stable temperature for the engine oil (and autobox fluid in many cases) to equalise to.

Engine oil temperature for optimal lubrication - jc2

Many cars-particularly turbos-both petrol and diesel-are fitted with devices that use the return water from the heater to cool the oil.At the start of a journey,because the coolant heats up first,some heat will be transferred to the oil.Commonest device is the "Modine" which is usually fitted between the filter and it's connection to the engine.

Engine oil temperature for optimal lubrication - SteveLee

An oil pressure gauge is the most inportant indicator as to whether an engine is warm enough to thrash. Sadly not many cars are fitted with them these days. Generally water temperature gauges are in their "normal" zones way, way before the oil is warm enough, the only way to tell the engine oil is warm enough is that the oil pressure drops off at idle.

Engine oil temperature for optimal lubrication - Cyd

80 - 100 C would be 'normal'. Short bursts up to 120C is acceptable but if your engine is sustaining this then an oil cooler would be required. Any higher (particularly if it's sustained) and you'll start to cook th eoil very quick. My Saabs oil cooler stat opens at 107C (it's an oil to water cooler). Always had an oil to air cooler on my rally cars with a 105C stat. You have to bear in mind that if your oil is getting too hot, then there's a good chance that other parts of the engine are too!

Engine oil temperature for optimal lubrication - Alf_Hooker
I hav a gauge on my car, temp is usually 95-100 c only goes above 100 when im driving at high speeds for sustained periods. I let it get over 75 before I start hammering it
Engine oil temperature for optimal lubrication - 5cylinderdiesel

Thank you for all the messages. So in practice go slow for at least 15 minitues of driving and then you can go crazy if you need to. If I want to make an effort to give my engine a good life so to speak what would be considered the ideal rev point to change gears during warm up? I'm thinking keep it below 2500 rpm for the first 15 min of driving for both diesel + petrol. Is this good thinking or incorrect? Thanks again.

Engine oil temperature for optimal lubrication - RT

For a diesel with a flat-topped torque curve, eg max quoted torque from 1800-2500 rpm - keep it between 1800 and 2500rpm until it's warmed up - probably best to stay in that range all the time unless you're "ragging" it.

Engine oil temperature for optimal lubrication - Cyd

I wouldn't adocate going slow then going 'crazy' (as you put it). Start off gently and build up the use of power over say 10 - 15 miles. It's acceleration and use of revs that need moderating particularly. Don't worry too much about cruising at 70 on a motorway after only a mile or two though - this is easy work.

Engine oil temperature for optimal lubrication - unthrottled

re petrols: I used to apply full throttle (but low revs) immediately after starting from cold and found that the oil was getting heavily contaminated with fuel which couldn't evaporate properly when the valves were cold. Keeping manifold vacuum high for a minute or two stopped this. Of course, this doesn't apply to diesels.

I would advocate gradually building the revs up. You don't need to maintain a 2500RPM ceiling for 20 minutes, but, personally, I don't redline it for at least 15 minutes.

Timing belts (if your engine has one) benefit from a warm up too.

Engine oil temperature for optimal lubrication - 72 dudes

Several of my cars have had an engine oil temperature gauge fitted, plus my MX5 has an oil pressure gauge.

Ambient temperature also plays a part, but for the first 5 miles, driving below 3000 RPM in a petrol engined car and 2500 RPM in a diesel engined car is my own personal yardstick.

Edited by 72 dudes on 26/05/2013 at 17:32

Engine oil temperature for optimal lubrication - 5cylinderdiesel

Thanks again for all the messages and advice. I roughly have the same theory 72 dudes. I try to stay below 2000 rpm and if I have to 2500 in my diesel and once the water temperature has reaches 'normal' I will go up to 3000 rpm again only if I need to. What I try to do every now and again is to take my engine revs up to 4000 rpm in 2nd and 3rd, but this I ideally only do on long journeys. If I haven't done a long journey in a while I will do it on my way home after work in the evening and only after I've done 14-15 miles on the motorway (perhaps this is slightly too quick??). Cheers

Engine oil temperature for optimal lubrication - Cyd

I try to stay below 2000 rpm and if I have to 2500 in my diesel

Careful you're not labouring the engine on upshifts. Far worse than a few more revs at low throttle.

 

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